Venous thromboembolism in patients with essential thrombocythemia and polycythemia vera

Identifying Patients with Polycythemia Vera at Risk of Thrombosis after Hydroxyurea Initiation: The Polycythemia Vera-Advanced Integrated Models (PV-AIM) Project

Patients with polycythemia vera (PV) are at significant risk of thromboembolic events (TE). The PV-AIM study used the Optum® de-identified Electronic Health Record dataset and machine learning to identify markers of TE in a real-world population. Data for 82,960 patients with PV were extracted: 3852 patients were treated with hydroxyurea (HU) only, while 130 patients were treated with HU and then changed to ruxolitinib (HU-ruxolitinib). For HU-alone patients, the annualized incidence rates (IR; per 100 patients) decreased from 8.7 (before HU) to 5.6 (during HU) but increased markedly to 10.5 (continuing HU). Whereas for HU-ruxolitinib patients, the IR decreased from 10.8 (before HU) to 8.4 (during HU) and was maintained at 8.3 (after switching to ruxolitinib). To better understand markers associated with TE risk, we built a machine-learning model for HU-alone patients and validated it using an independent dataset. The model identified lymphocyte percentage (LYP), neutrophil percentage (NEP), and red cell distribution width (RDW) as key markers of TE risk, and optimal thresholds for these markers were established, from which a decision tree was derived. Using these widely used laboratory markers, the decision tree could be used to identify patients at high risk for TE, facilitate treatment decisions, and optimize patient management.

Kidney Dysfunction Is Associated with Thrombosis and Disease Severity in Myeloproliferative Neoplasms: Implications from the German Study Group for MPN Bioregistry

Simple Summary

In patients with myeloproliferative neoplasms (MPN) and in patients with kidney dysfunction, a higher rate of thrombosis has been reported compared with the general population. Furthermore, MPN patients are more prone to develop kidney dysfunction. In our study, we assessed the importance of specific risk factors for kidney dysfunction and thrombosis in MPN patients. We found that the rate of thrombosis is correlated with the degree of kidney dysfunction, especially in myelofibrosis. Significant associations for kidney dysfunction included arterial hypertension, MPN treatment, and increased inflammation, and those for thrombosis comprised arterial hypertension, non-excessive platelet counts, and antithrombotic therapy. The identified risk factor associations varied between MPN subtypes. Our data suggest that kidney dysfunction in MPN patients is associated with an increased risk of thrombosis, mandating closer monitoring, and, possibly, early thromboprophylaxis.

Abstract

Inflammation-induced thrombosis represents a severe complication in patients with myeloproliferative neoplasms (MPN) and in those with kidney dysfunction. Overlapping disease-specific attributes suggest common mechanisms involved in MPN pathogenesis, kidney dysfunction, and thrombosis. Data from 1420 patients with essential thrombocythemia (ET, 33.7%), polycythemia vera (PV, 38.5%), and myelofibrosis (MF, 27.9%) were extracted from the bioregistry of the German Study Group for MPN. The total cohort was subdivided according to the calculated estimated glomerular filtration rate (eGFR, (mL/min/1.73 m²)) into eGFR1 (≥90, 21%), eGFR2 (60–89, 56%), and eGFR3 (<60, 22%). A total of 29% of the patients had a history of thrombosis. A higher rate of thrombosis and longer MPN duration was observed in eGFR3 than in eGFR2 and eGFR1. Kidney dysfunction occurred earlier in ET than in PV or MF. Multiple logistic regression analysis identified arterial hypertension, MPN treatment, increased uric acid, and lactate dehydrogenase levels as risk factors for kidney dysfunction in MPN patients. Risk factors for thrombosis included arterial hypertension, non-excessive platelet counts, and antithrombotic therapy. The risk factors for kidney dysfunction and thrombosis varied between MPN subtypes. Physicians should be aware of the increased risk for kidney disease in MPN patients, which warrants closer monitoring and, possibly, early thromboprophylaxis.

Does race play a role in complications and outcomes of Philadelphia chromosome-negative myeloproliferative neoplasms?

BACKGROUND

Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) are a group of hematologic malignancies with known vascular complications. The role race and ethnicity play in these complications is less defined. We aimed to further evaluate the role of race in patients without a history of previous thrombotic or hemorrhagic events.

METHODS

In this retrospective study, 300 adult patients with MPN were included; 270 (90.0%) were White and 30 (10.0%) were non-White. The non-White group primarily consisted of African American or Black (26 patients), followed by others. Median age at diagnosis was 58 years for White patients and 61.5 years for non-White patients. The interaction between outcomes and vascular events with race was evaluated using multivariate logistical regression models.

RESULTS

The incidence of thrombotic events was inversely correlated with age at diagnosis, with younger patients demonstrating a higher rate of thrombotic events over time (p < .001). The incidence of thrombotic or hemorrhagic events did not differ between White and non-White patients. A statistically significant difference in median survival was observed between White and non-White patients: 29 years (95% confidence interval [CI]: 21.8-not reached) versus 13 years (95% CI: 5.7-22.7), respectively (p = .016).

CONCLUSION

This study did not find a significant difference in the rate of thrombotic or hemorrhagic events between White and non-White patients with MPN but suggested that non-White patients had significantly shorter median survival than White patients. Such observations may inform future studies to further characterize racial disparities in outcomes.

Prevalence of definite antiphospholipid syndrome in carriers of the JAK2V617F mutation

INTRODUCTION

Patients with Philadelphia-negative myeloproliferative neoplasms (MPNs), particularly those carrying the JAK2^V617F mutation, are at increased risk of thrombosis. While an association of MPNs with autoimmune disorders has been established, the prevalence of inherited or acquired thrombophilias in JAK2^V617F-positive patients remains obscure. We therefore investigated the coincidence of the JAK2^V617F mutation with additional thrombogenic risk factors.

METHODS

In a retrospective study, we analyzed all patients referred for thrombophilia work-up between 01/2011 and 08/2019, in whom additional JAK2^V617F mutation analysis was performed because of thromboembolic events that were recurrent, atypically located and/or associated with abnormal blood counts.

RESULTS

Of 472 tested patients, 49 (10.4%) were JAK2^V617F-positive. While the frequency of inherited thrombophilias (factor V Leiden and prothrombin G20210A mutation, deficiency of antithrombin, protein C, protein S) was not different between the two groups, the prevalence of definite antiphospholipid syndrome (APS), mostly associated with a moderate- or high-risk antibody profile, was significantly higher in patients with (22.4%) than in those without (8.4%) JAK2^V617F mutation (p < 0.01). All evaluable JAK2^V617F-positive patients with APS were subsequently diagnosed with MPN. In patients with JAK2^V617F mutation, presence of concomitant APS was associated with a significantly younger age (49 ± 14 vs. 60 ± 15 years) at the time of thrombophilia work-up (p < 0.05).

CONCLUSION

We found a significant association between JAK2^V617F-positive MPN and definite APS. The presence of concomitant APS in patients carrying the JAK2^V617F mutation may lead to earlier manifestation of thromboembolic events and may warrant more aggressive antithrombotic treatment strategies to prevent recurrence.

What cardiologists should know about essential thrombocythemia and acute myocardial infarction: report of two cases and advanced heart failure therapies considerations

We present the cases of two young male patients aged 22 and 31 without prior medical history nor cardiovascular risk factors, who presented to the hospital with large anterior ST-elevation myocardial infarction (STEMI). Urgent coronary angiography revealed acute thrombotic occlusion of the proximal left anterior descending artery in both patients. Persistent thrombocytosis was noted and subsequent investigations led to the diagnosis of essential thrombocythemia (ET) with positive JAK2-V617F mutation. Myocardial infarction as a first clinical manifestation of ET is rare but must be considered in patients without cardiovascular risk factors who show persistent thrombocytosis. In young patients without risk factors, there may be great delays before the diagnosis of STEMI is made. Longer time to revascularization of extensive STEMI is associated with adverse outcomes and cardiogenic shock which can lead to advanced therapies like heart transplant and left ventricular assist device (LVAD). Considering the favorable long-term prognosis of patients with ET, advanced therapies may be a valuable option in the presence of severe left ventricular dysfunction.

Re-evaluation of hematocrit as a determinant of thrombotic risk in erythrocytosis

Here we critically evaluate the role of elevated hematocrit as the principal determinant of thrombotic risk in polycythemia and erythrocytosis, defined by an expansion of red cell mass. Since red cell volume determination is no longer readily available, in clinical practice, polycythemia and erythrocytosis are defined by elevated hemoglobin and hematocrit. Thrombosis is common in Chuvash erythrocytosis and polycythemia vera. Although the increased thrombotic risk is assumed to be due to the elevated hematocrit and an associated increase in blood viscosity, thrombosis does not accompany most types of erythrocytosis. We review studies indicating that the occurrence of thrombosis in Chuvash erythrocytosis is independent of hematocrit, that the thrombotic risk is paradoxically increased by phlebotomy in Chuvash erythrocytosis, and that, when compared to chemotherapy, phlebotomy is associated with increased thrombotic risk in polycythemia vera. Inherited and environmental causes that lead to polycythemia and erythrocytosis are accompanied by diverse cellular changes that could directly affect thrombotic risk, irrespective of the elevated hematocrit. The pressing issue in these disorders is to define factors other than elevated hematocrit that determine thrombotic risk. Defining these predisposing factors in polycythemia and erythrocytosis should then lead to rational therapies and facilitate development of targeted interventions.

Philadelphia chromosome positive AML arising from JAK2-positive myelofibrosis

Background

A feature of myeloproliferative neoplasia is transforming to more aggressive and malignant myeloid neoplasia, including acute myeloid leukemia. Different pathogenesis mechanisms participate in transformation, including transformation of existing potential preleukemic clones, since JAK2-mutant myeloproliferative neoplasms often transform to JAK2 wild-type acute myeloid leukemia.

Case presentation

Here, we present an 80 year old man with a JAK2-V617F mutant primary myelofibrosis. After 10 months the disease transform into a Philadelphia chromosome positive acute myeloid leukemia, detecting the cytogenetic aberration; t(9;22)(q34;q22) encoding the rare BCR-ABL1 fusion gene; e6a2. The patient had treatment response to tyrosine kinases, illustrating the potential benefits of such approach in treating these patients subset.

Conclusion

The case illustrates the potential of leukemic transformation to Philadelphia chromosome positive myeloid malignancies from potential existing preleukemic clones, and the awareness of such an evolution among patients with myeloproliferative neoplasms. Tyrosine kinases have potential effect also in patients presenting without chronic myeloid leukemia and with rare BCR-ABL1 fusion transcripts, and should probably be a part of the treatment approach.

An evaluation of global coagulation assays in myeloproliferative neoplasm

: Myeloproliferative neoplasms (MPN) are independent risks for thrombotic events. Routine laboratory tests are inadequate to evaluate the underlying procoagulant state. Global coagulation assays such as thromboelastography, thrombin and fibrin generation may provide better assessment of coagulation activation and thereby of thrombosis risk. Participants with MPN were recruited. Thromboelastography was performed on citrated whole blood while thrombin generation using calibrated automated thrombogram, fibrin generation using overall haemostatic potential assays and P-selectin were quantified on platelet-poor plasma. Thirty-eight MPN patients (median age: 65 years) were recruited. There were 26 patients with essential thrombocythemia (68.4%), eight polycythemia vera (20.5%), three primary myelofibrosis and one MPN, unclassifiable. Compared with normal controls, there was no difference in maximum amplitude although lysis time (LY30) was significantly higher (2.9 vs. 0.6%, adjusted P < 0.01) using thromboelastography. Calibrated automated thrombogram showed higher thrombin peak (260.8 vs. 222.6 nmol/l; P < 0.01) and velocity index (91.1 vs. 65.0 nmol/l/min; P < 0.01) with comparable endogenous thrombin potential. Fibrin generation parameters were significantly reduced with preserved overall fibrinolytic potential, whereas P-selectin was markedly increased (108.9 vs. 49.3 ng/ml, P < 0.01). This study demonstrated unique differences between MPN population and normal controls using a combination of global coagulation assays. The presence of high lysis time (LY30) and reduced fibrin generation in MPN patients were contradictory to the prothrombotic nature and may represent a compensatory effort to achieve equilibrium within the Virchow's triad. Both markers may be important prognostic indicators of thrombosis in MPN and further prospective studies to confirm these findings are proposed.

Hypercoagulable States and Thrombophilias: Risks Relating to Recurrent Venous Thromboembolism

Inherited and acquired thrombophilias and hypercoagulable states, such as active cancer, estrogen-induced, autoimmune disorders, major surgery, hospitalization, and trauma, are well-known risk factors for venous thromboembolism (VTE). The effect of these on recurrent VTE is different for each specific risk factor. The major risk factors affecting VTE recurrence include the presence of active cancer and an unprovoked first VTE. In addition, the use of combined female hormones in a woman with a previous history of estrogen-related VTE is a major risk factor for VTE recurrence. The extent of influence of inherited thrombophilia on the risk of recurrence is controversial. Conversely, the presence of antiphospholipid antibodies, specifically triple positive carriers, appears to increase the risk of VTE recurrence. Understanding the rates of recurrent VTE in a patient and the individual risk of bleeding is important in determining the duration of anticoagulation therapy.

Phosphatidylserine-exposing blood and endothelial cells contribute to the hypercoagulable state in essential thrombocythemia patients

The mechanisms of thrombogenicity in essential thrombocythemia (ET) are complex and not well defined. Our objective was to explore whether phosphatidylserine (PS) exposure on blood cells and endothelial cells (ECs) can account for the increased thrombosis and distinct thrombotic risks among mutational subtypes in ET. Using flow cytometry and confocal microscopy, we found that the levels of PS-exposing erythrocytes, platelets, leukocytes, and serum-cultured ECs were significantly higher in each ET group [JAK2, CALR, and triple-negative (TN) (all P < 0.001)] than those in controls. Among ET patients, those with JAK2 mutations showed higher levels of PS-positive erythrocytes, platelets, neutrophils, and serum-cultured ECs than TN patients or those with CALR mutations, which show similar levels. Coagulation function assays showed that higher levels of PS-positive blood cells and serum-cultured ECs led to markedly shortened coagulation time and dramatically increased levels of FXa, thrombin, and fibrin production. This procoagulant activity could be largely blocked by addition of lactadherin (approx. 70% inhibition). Confocal microscopy showed that the FVa/FXa complex and fibrin fibrils colocalized with PS on ET serum-cultured ECs. Additionally, we found a relationship between D-dimer, prothrombin fragment F1 + 2, and PS exposure. Our study reveals a previously unrecognized link between hypercoagulability and exposed PS on cells, which might also be associated with distinct thrombotic risks among mutational subtypes in ET. Thus, blocking PS-binding sites may represent a new therapeutic target for preventing thrombosis in ET.

Age-Related Macular Degeneration in Patients With Chronic Myeloproliferative Neoplasms

Importance

It has been suggested that systemic inflammation increases the risk of age-related macular degeneration (AMD). Given that chronic immune modulation is present in patients with myeloproliferative neoplasms (MPNs), the risk of AMD in these patients may be increased.

Objective

To compare the risk of AMD in patients with MPNs with the risk of AMD in matched controls from the general population.

Design, Setting, and Participants

A nationwide population-based cohort study using Danish registers was conducted of all patients in Denmark who received a diagnosis between January 1, 1994, and December 31, 2013, of essential thrombocythemia, polycythemia vera, myelofibrosis, or unclassifiable MPNs. For each patient, 10 age- and sex-matched controls were included. All patients without prior AMD were followed up from the date of diagnosis (or corresponding entry date for the controls) until the first AMD diagnosis, death or emigration, or December 31, 2013, whichever occurred first. Data analysis was performed from April 1, 2015, to October 31, 2016.

Main Outcomes and Measures

Incidence of AMD recorded in specialized hospital-based care. The rates and absolute risk of AMD were calculated. Using Cox proportional hazards regression models, smoking and risk-time adjusted hazard ratios (HRs) between patients and controls were calculated. In addition, HRs of neovascular AMD after 2006 were calculated since antivascular endothelial growth factor treatment was introduced nationwide at hospitals thereafter.

Results

A total of 7958 patients with MPNs (4279 women [53.8%] and 3679 men [46.2%]; mean [SD] age at diagnosis, 66.4 [14.3] years) were included in the study. The rate of AMD per 1000 person-years at risk was 5.2 (95% CI, 4.6-5.9) for patients with MPNs (2628 with essential thrombocythemia, 3063 with polycythemia vera, 547 with myelofibrosis, and 1720 with unclassifiable MPNs) and 4.3 (95% CI, 4.1-4.4) for the 77 445 controls, while the 10-year risk of AMD was 2.4% (95% CI, 2.1%-2.8%) for patients with MPNs and 2.3% (95% CI, 2.2%-2.4%) for the controls. The risk of AMD was increased overall for patients with MPNs (adjusted HR, 1.3; 95% CI, 1.1-1.5), with adjusted HRs for the subtypes of 1.2 (95% CI, 1.0-1.6) for essential thrombocythemia, 1.4 (95% CI, 1.2-1.7) for polycythemia vera, 1.7 (95% CI, 0.8-4.0) for myelofibrosis, and 1.5 (95% CI, 1.1-2.1) for unclassifiable MPNs. In addition, patients with MPNs had a higher risk of neovascular AMD (adjusted HR, 1.4; 95% CI, 1.2-1.6).

Conclusions and Relevance

Our results suggest that patients with MPNs are at increased risk of AMD, supporting the possibility that systemic inflammation is involved in the pathogenesis of AMD.

Estimation of diagnosis and prognosis in ET by assessment of CALR and JAK2V617F mutations and laboratory findings: a meta-analysis

BACKGROUND

Essential thrombocythemia (ET) is a benign disease with slow progress in which thrombosis is a cause of mortality. JAK2^V617F and calreticulin (CALR) are the most frequent mutations in this disease. In this systematic review and meta-analysis, we compared the prevalence of JAK2^V617F and CALR mutations in ET and examined the incidence of thrombosis and other hematologic indices.

METHODS

After choosing MeSH keywords, including essential thrombocythemia, JAK2^V617F, calreticulin, prognosis, and diagnosis, as well as searching Medline/PubMed and Scopus, 12 papers were selected. Data were pooled, and summary prevalence and OR were estimated using either a random-effects model or a fixed-effects model.

RESULTS

The frequency of JAK2^V617F and CALR shows heterogeneity in Caucasian population [JAK2^V617 I ²% = 84.3, P < 0.001, 95% CI 0.56 (0.51-0.61)], [CALR I ²% = 96.1, P < 0.001, 95% CI 0.23 (0.15-0.31)]. The prevalence of JAK2^V617F and CALR was 0.57 (95% CI 0.53-0.61), I ²% = 79.3 and 0.22 (95% CI 0.16-0.27), I ²% = 94, respectively. JAK2^V617F positive ET was associated with increasing odds of thrombosis [OR 2.35 (95% CI 1.83-3.02), P < 0.001]. The incidence of splenomegaly was not statistically different between these two mutations. Hemoglobin, platelet, and WBC count did not affect the risk of thrombosis.

CONCLUSIONS

Detection of CALR mutation is helpful for molecular diagnosis of ET patients as well as JAK2^V617F. Due to reduction of thrombosis in CALR-positive patients, it can be stated that such patients have less thrombotic disorders and better prognosis relative to patients bearing JAK2^V617F mutation. Therefore, detection of mutation in CALR and JAK2^V617F may contribute to diagnosis and prognosis of ET patients.

An Overview of Thrombophilia and Associated Laboratory Testing

Venous thromboembolism, usually entailing deep vein thrombosis, pulmonary embolism, or both, is a complex and multifactorial disorder, in which a number of putative conditions interplay and finally contribute to propel the individual risk over a certain degree, so ultimately culminating in the development of venous occlusive disorders. Thrombophilia is commonly defined as a propensity to develop venous thromboembolism on the basis of an underlying hypercoagulable state attributable to inherited or acquired disorders of blood coagulation or fibrinolysis. The thrombophilic conditions are conventionally classified as inherited (or genetically determined) and acquired. The former include deficiencies of natural anticoagulants such as antithrombin, protein C, protein S, increased values of clotting factors (especially factor VIII), as well as prothrombotic polymorphisms in genes encoding for factor V (i.e., factor V Leiden) and prothrombin. The latter conditions mainly entail antiphospholipid antibody syndrome, malignancy, acquired elevations of coagulation factors or acquired reduction of natural inhibitors, or hyperhomocysteinemia. Deepened knowledge of all potential risk factors, as well as the clear understanding of their role in the pathophysiology of venous thrombosis, are both essential to help achieve a faster and more efficient diagnosis of this condition as well as a more effective prophylaxis of patients at higher risk and treatment of those with manifest disease.

Haemostatic Profile in Patients of Myeloproliferative Neoplasms-A Tertiary Care Centre Experience

INTRODUCTION

Patients of MPN commonly present with abnormalities in laboratory coagulation tests that are consistent with hypercoagulable state. Some individuals with MPN exhibit a pattern of exclusive bleeding or thrombotic events; many others have both bleeding and thrombosis during the course of the disease.

AIM

This study was undertaken to assess the haemostatic defects and platelet functions in patients of MPN.

MATERIALS AND METHODS

One year prospective study was conducted at a tertiary care centre in North India in Department of Pathology in collaboration with Department of Clinical Haematology. All recently diagnosed cases of MPN along with 30 age and sex matched controls were included. Patients on antiplatelet drugs, antimyeloproliferative treatment, vitamin K agonists or antagonists, OCPs, Platelet count <1,00,000/μl, high grade fever, liver disease, pregnancy were excluded from this study. All the patients underwent screening investigations like CBC, peripheral smear evaluation, BT, PT, aPTT, Protein C and S measurement (clot based assay) and aggregation studies with ADP (5μM) (Optical Aggregometry with AGGRO/LINK 8 software and CHRONOLOG 700 aggregometer).

RESULTS

In present study, 50 cases were included. There was an occult prothrombotic state, suggested by significantly (p<0.001) reduced levels of Protein C and Protein S, but no patient presented with frank thrombosis while 8 out of 50 patients had haemorrhagic manifestations ranging from subdural haematoma to pin point petechial haemorrhages. Patients of CML-CP, ET, PV, PMF, MPN-NOS showed significantly reduced maximal aggregation with ADP (5μM) when compared to control (p<0.001). MPV also showed a statistically significant increase in these patients.

CONCLUSION

Thrombohaemorrhagic complications significantly affect the morbidity and mortality of MPN patients. This can be assessed by the use of platelet aggregation studies, Protein C and S activities and other coagulation studies. Timely diagnosis of these prothrombotic/haemorrhagic states can decrease the morbidity in these patients.

Thromboembolic risk in hematological malignancies

There are a growing number of studies documenting that, similarly to patients with solid cancers, also patients with hematological malignancies (i.e., acute leukemia, lymphoproliferative and myeloproliferative neoplasms and plasma cell disorders) are at increased risk of thrombosis. The pathogenesis of the hypercoagulable state associated with hematological cancers is often multifactorial. Contributor factors include tumor cell-derived procoagulants, antineoplastic therapies, central venous catheters, concomitant infections and advanced age. In this narrative review, the epidemiology, pathogenesis and management of thrombosis in patients with hematological malignancies are reviewed.

Bleeding, thrombosis, and anticoagulation in myeloproliferative neoplasms (MPN): analysis from the German SAL-MPN-registry

BACKGROUND

Patients with Ph-negative myeloproliferative neoplasms (MPN), such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are at increased risk for thrombosis/thromboembolism and major bleeding. Due to the morbidity and mortality of these events, antiplatelet and/or anticoagulant agents are commonly employed as primary and/or secondary prophylaxis. On the other hand, disease-related bleeding complications (i.e., from esophageal varices) are common in patients with MPN. This analysis was performed to define the frequency of such events, identify risk factors, and assess antiplatelet/anticoagulant therapy in a cohort of patients with MPN.

METHODS

The MPN registry of the Study Alliance Leukemia is a non-interventional prospective study including adult patients with an MPN according to WHO criteria (2008). For statistical analysis, descriptive methods and tests for significant differences as well as contingency tables were used to identify the odds of potential risk factors for vascular events.

RESULTS

MPN subgroups significantly differed in sex distribution, age at diagnosis, blood counts, LDH levels, JAK2V617F positivity, and spleen size (length). While most thromboembolic events occurred around the time of MPN diagnosis, one third of these events occurred after that date. Splanchnic vein thrombosis was most frequent in post-PV-MF and MPN-U patients. The chance of developing a thromboembolic event was significantly elevated if patients suffered from post-PV-MF (OR 3.43; 95% CI = 1.39-8.48) and splenomegaly (OR 1.76; 95% CI = 1.15-2.71). Significant odds for major bleeding were previous thromboembolic events (OR = 2.71; 95% CI = 1.36-5.40), splenomegaly (OR = 2.22; 95% CI 1.01-4.89), and the administration of heparin (OR = 5.64; 95% CI = 1.84-17.34). Major bleeding episodes were significantly less frequent in ET patients compared to other MPN subgroups.

CONCLUSIONS

Together, this report on an unselected "real-world" cohort of German MPN patients reveals important data on the prevalence, diagnosis, and treatment of thromboembolic and major bleeding complications of MPN.

Neurological symptoms in essential thrombocythemia: impact of JAK2V617F mutation and response to therapy

Patients with essential thrombocythemia (ET) often suffer from neurological symptoms (NS) not ever resulting from previous thrombotic cerebral events (TCE). We reported NS occurred in 282 patients, in order to identify the factors influencing ET-related NS in the absence of TCE, and the response to therapy. Overall, 116 of 282 patients (41%) presented NS; 101 of them (87%) reported subjective transient and fluctuating NS, without concurrent TCE, which we defined as ET-related NS, by frequency: cephalalgia, chronic paresthesias, dizziness or hypotension, visual disturbances, and tinnitus. In univariate analysis, ET-related NS resulted more frequently in young people (P = 0.017) and in females (P = 0.025). We found a higher prevalence of JAK2V617F mutation in ET-related NS patients (P = 0.021). In multivariate analysis, gender (P = 0.024) and JAK2V617F mutation (P = 0.041) remained significantly associated with the development of ET-related NS, with a risk of about four times higher for JAK2V617F-mutated patients (OR = 3.75). Ninety-seven of 101 patients with ET-related NS received an antiplatelet (AP) agent at the time of NS, whereas only selected high-risk ET-related NS patients were treated with a cytoreductive drug, according to the published guidelines and similarly to patients without NS. We observed that only 32 of 97 (33%) patients with ET-related NS achieved a complete response after AP treatment. Among the 65 non-responder patients, 36 (55.4%) improved NS after the introduction of cytoreductive therapy; therefore, the addition of cytoreductive treatment should be considered in this setting.

Oral anticoagulation to prevent thrombosis recurrence in polycythemia vera and essential thrombocythemia

It is unclear whether anticoagulation guidelines intended for the general population are applicable to patients with polycythemia vera (PV) and essential thrombocythemia (ET). In the present study, the risk of thrombotic recurrence was analyzed in 150 patients with PV and ET treated with vitamin K antagonists (VKA) because of an arterial or venous thrombosis. After an observation period of 963 patient-years, the incidence of re-thrombosis was 4.5 and 12 per 100 patient-years under VKA therapy and after stopping it, respectively (P < 0.0005). After a multivariate adjustment for other prognostic factors, VKA treatment was associated with a 2.8-fold reduction in the risk of thrombotic recurrence. Notably, VKA therapy offset the increased risk of re-thrombosis associated with a prior history of remote thrombosis. Both the protective effect of VKA therapy and the predisposing factors for recurrence were independent of the anatomical site involved in the index thrombosis. Treatment periods with VKA did not result in a higher incidence of major bleeding as compared with those without VKA. These findings support the use of long-term anticoagulation for the secondary prevention of thrombosis in patients with PV and ET, particularly in those with history of remote thrombosis.

Stalled cerebral capillary blood flow in mouse models of essential thrombocythemia and polycythemia vera revealed by in vivo two-photon imaging

BACKGROUND

Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) that share the JAK2(V617F) mutation in hematopoietic stem cells, leading to excessive production of predominantly platelets in ET, and predominantly red blood cells (RBCs) in PV. The major cause of morbidity and mortality in PV and ET is thrombosis, including cerebrovascular occlusive disease.

OBJECTIVES

To identify the effect of excessive blood cells on cerebral microcirculation in ET and PV.

METHODS

We used two-photon excited fluorescence microscopy to examine cerebral blood flow in transgenic mouse models that mimic MPNs.

RESULTS AND CONCLUSIONS

We found that flow was 'stalled' in an elevated fraction of brain capillaries in ET (18%), PV (27%), mixed MPN (14%) and secondary (non-MPN) erythrocytosis (27%) mice, as compared with controls (3%). The fraction of capillaries with stalled flow increased when the hematocrit value exceeded 55% in PV mice, and the majority of stalled vessels contained only stationary RBCs. In contrast, the majority of stalls in ET mice were caused by platelet aggregates. Stalls had a median persistence time of 0.5 and 1 h in ET and PV mice, respectively. Our findings shed new light on potential mechanisms of neurological problems in patients with MPNs.

The JAK2 V617F mutational status and allele burden may be related with the risk of venous thromboembolic events in patients with Philadelphia-negative myeloproliferative neoplasms

INTRODUCTION

Patients with Philadelphia-negative myeloproliferative neoplasms (Ph(-) MPNs) are at increased risk of thromboembolic and hemorrhagic complications. The aim of the study was to determine the relationship between JAK2 V617F mutational status, JAK2 V617F allele burden and the risk of vascular complications occurrence.

MATERIALS AND METHODS

Analysis was performed in a cohort of 186 patients diagnosed with polycythemia vera (53), essential thrombocythemia (114), primary myelofibrosis (11), and unclassified MPN (8). The risk of vascular complications development was analyzed in 126 JAK2 V617F-positive patients with respect to allele burden assessed with allele-specific 'real-time' quantitative polymerase chain reaction (AS RQ-PCR).

RESULTS

Overall prevalence of any vascular complications was 44.6%. Arterial thrombosis occurred in 20.4%, venous thromboembolism (VTE) in 11.3%, bleeding episodes in 24.7% of patients. Individuals harboring JAK2 V617F mutation, regardless of MPN type, were at higher risk of VTE (OR=5.15, 95%CI: 1.16-22.90, P=0.024), mainly deep vein thrombosis (DVT). JAK2 allele burden higher than 20% identified patients with 7.4-fold increased risk of VTE (95%CI: 1.6-33.7, P=0.004), but not of arterial thrombosis, neither of bleeding complications, and remained the only significant VTE risk factor in multivariate logistic regression. High allele burdens (over 50%) were strikingly associated with proximal DVT cases, but not with distal DVT.

CONCLUSIONS

The group of MPN patients with JAK2 V617F allele burden higher than 20% may benefit the most from vigilant monitoring and appropriate prophylaxis against vascular events. Inclusion of JAK2 V617F mutant allele burden in new risk stratifications seems to be justified and requires controlled prospective trials.

Prophylaxis and management of venous thromboembolism in patients with myeloproliferative neoplasms: consensus statement of the Haemostasis Working Party of the German Society of Hematology and Oncology (DGHO), the Austrian Society of Hematology and Oncology (ÖGHO) and Society of Thrombosis and Haemostasis Research (GTH e.V.)

Patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) like polycythemia vera and essential thrombocythemia are at increased risk of arterial and venous thrombosis. Strategies of prevention may consist of platelet aggregation inhibitors and/or cytoreductive agents depending on the underlying disease and the individual risk. Clinical evidence for management of acute venous thromboembolic events in MPN patients is limited. Modality and duration of therapeutic anticoagulation after venous thrombosis has to be evaluated critically with special regard to the increased risk for spontaneous bleeding events associated with the underlying diseases. Both for therapy of the acute event and for secondary prophylaxis, low-molecular-weight heparins should preferentially be used. A prolongation of the therapeutic anticoagulation beyond the usual 3 to 6 months can only be recommended in high-risk settings and after careful evaluation of potential risks and benefits for the individual patient. New direct oral anticoagulants (NOAC) should not preferentially be used due to lack of clinical experience in patients with MPN and potential drug interactions (e.g. with JAK inhibitors). Consequent treatment of the underlying myeloproliferative disease and periodical evaluation of the response to therapy is crucial for optimal secondary prophylaxis of thromboembolic events in those patients.

Haemorrhagic and thrombotic diatheses in mouse models with thrombocytosis

We studied haemostasis in two mouse models with thrombocytosis caused by different pathogenic mechanisms. In one strain (Yall;Mpl-/-) thrombocytosis is driven by a misbalance between thrombopoietin and its receptor, whereas in the other strain, thrombocytosis is caused by expressing a human JAK2-V617F transgene (FF1) that depends on activation by Cre-recombinase (VavCre;FF1, MxCre;FF1). Thrombotic responses were increased following some, but not all types of challenges. In a vaso-occlusive thrombotic model following collagen-adrenaline injection we found increased mortality in both strains. Arterial thrombosis, examined after ferric chloride-induced carotid injury, was accelerated but with little impact on maximal thrombus size. In a vena cava stasis model, clots were of similar size as in wild-type controls, but exhibited a different composition with a higher platelet to fibrin ratio. Both thrombocytosis strains displayed increased haemorrhagic tendency in a tail bleeding assay. Yall;Mpl and VavCre;FF1 displayed a lower proportion of the more reactive high-molecular-weight forms of von Willebrand factor in their plasma, mimicking essential thrombocythaemia with very high platelet counts. Bleeding could not be explained by clear defects in platelet activation, which were normal or only weakly decreased. In conclusion, these models of thrombocytosis recapitulate several features of the haemorrhagic and thrombotic diatheses in ET and PV demonstrating potentials but also some limitations to study these major complications.

Systemic levels of the endothelium-derived soluble adhesion molecules endocan and E-selectin in patients with suspected deep vein thrombosis

The initial evaluation of patients with suspected deep vein thrombosis includes the use of biomarkers reflecting activation of the coagulation system. However, the thromboembolic process and neighboring inflammatory responses also affect endothelial cells, and endothelial cell markers may therefore be altered by the disease. In the present population-based single-center study, we investigated the plasma levels of the endothelium-specific biomarkers soluble E-selectin and endocan in a consecutive and unselected group of 120 patients admitted to hospital for suspected deep vein thrombosis. Blood samples were collected when patients arrived at the hospital. DVT patients showed evidence for an acute phase reaction with increased serum C-reactive protein levels, but this was similar to many other patients admitted with suspected but not verified thrombosis. Plasma endocan and E-selectin levels did not differ between patients with thrombosis, healthy controls and the patients without verified thrombosis (i.e. patients with other causes of their symptoms, including various inflammatory and non-inflammatory conditions). However, the combined use of endothelial biomarkers, C-reactive protein and D-dimer could be used to identify patient subsets with different frequencies of venous thrombosis. Thus, analysis of plasma biomarker profiles including endothelial cell markers may be helpful in the initial evaluation of patients with deep vein thrombosis.

Assessing the risk and prognosis of thrombotic complications in cancer patients

CONTEXT

Cancer is characterized by the development of a prothrombotic state. Approximately 15% to 20% and 1.5% to 3.1% of cancer patients develop venous and arterial thrombosis, respectively, whereas 18% to 20% of idiopathic venous events are caused by an occult neoplasia. The highest risk is observed in hematologic, gastrointestinal, and lung malignancies, as well as in patients with active disease, especially in the first 3 months after cancer diagnosis. Hospitalization, surgical interventions, and implanted venous devices increase the thrombotic risk. Patients with metastatic disease, febrile neutropenia, infections, and severe comorbidities experience more frequently a thrombotic event. A contemporary prechemotherapy predictive model incorporates both clinical and biologic parameters, such as the primary cancer site, platelet count, white blood cell count, hemoglobin, use of erythropoietic agents, and body mass index. Several studies aim to clarify the prognostic value of tissue factor, P-selectin, thrombin generation, microparticles, and D-dimers.

OBJECTIVES

To summarize current views on epidemiology, risk factors, and predictive variables, discussing the future perspectives and existing limitations in clinical practice.

DATA SOURCES

Review of published literature, including review papers, epidemiologic studies, and clinical trials, in online medical databases.

CONCLUSIONS

The thrombogenic properties of tumor cells affect the prognosis and quality of life for the cancer population. Despite the improved awareness and prompt use of thromboprophylaxis, recent studies reported increased rates of thrombotic events, whereas the annual risks for thrombosis recurrence and bleeding are 21% and 12%, respectively. The clinical use of risk factors and prognostic parameters could allow for patient risk stratification and individualization of anticoagulant treatment.

Splanchnic vein thrombosis in myeloproliferative neoplasms

Splanchnic vein thrombosis (SVT) is one of the most important complications of myeloproliferative neoplasms (MPN). Although MPN are common causes of SVT, the pathophysiological mechanisms underlying this predisposition, their epidemiology and natural history are not fully understood. Studies have concentrated on the generalized prothrombotic environment generated by MPN and their relationship with abnormal blood counts, thereby furthering our knowledge of arterial and venous thrombosis in this population. In contrast, there are few studies that have specifically addressed SVT in the context of MPN. Recent research has demonstrated in patients with MPN the existence of factors increasing the risk of SVT such as the presence of the JAK2 V617F mutation and its 46/1 haplotype. Features unique to the circulating blood cells, splanchnic vasculature and surrounding micro-environment in patients with MPN have been described. There are also abnormalities in local haemodynamics, haemostatic molecules, the spleen, and splanchnic endothelial and endothelial progenitor cells. This review considers these important advances and discusses the contribution of individual anomalies that lead to the development of SVT in both the pre-neoplastic and overt stage of MPN. Clinical issues relating to epidemiology, recurrence and survival in these patients have also been reviewed and their results discussed.

Coagulation and cancer: biological and clinical aspects

Malignancy affects the hemostatic system and the hemostatic system affects malignancy. In cancer patients there are a number of coagulation abnormalities which provide the background for an increased tendency of these patients to both thrombosis and hemorrhage. The causes of this coagulation impairment rely on general risk factors which are common to other categories of patients, and other factors which are specific to cancer, such as tumor type and disease stage. In addition, data from basic research indicate that the hemostatic components and the cancer biology are interconnected in multiple ways. Notably, while cancer cells are able to activate the coagulation system, the hemostatic factors play a role in tumor progression. This opens the way to the development of bifunctional therapeutic approaches that are both capable of attacking the malignant process and resolving the coagulation impairment. On the other hand, the management of thrombosis and hemorrhages in cancer patients can be different. To approach these problems, some guidelines have been released by prominent international scientific societies. Also actively investigated is the issue of identifying new biomarkers to classify the subjects at a higher risk, thus improving the prevention of thrombohemorrhagic events in these patients. Finally, novel prophylactic and therapeutic approaches are currently under development. This review provides an overview of the hemostatic complications in cancer, together with new insights into the interaction between hemostasis and cancer biology. We also review the assessment of the risk of thrombohemorrhagic events in cancer patients, and the prophylaxis and treatment of such manifestations.

Thrombotic disease in the myeloproliferative neoplasms

Thrombosis is a leading cause of morbidity and mortality in patients with Philadelphia chromosome–negative myeloproliferative neoplasms (MPNs), particularly polycythemia vera and essential thrombocythemia. Mechanisms involved in the pathogenesis of the acquired thrombophilic state associated with these diseases include abnormalities of MPN clone–derived blood cells, which display prothrombotic features, and abnormalities of normal vascular cells, which become procoagulant in response to inflammatory stimuli. Ultimately, the release into the blood of elevated levels of procoagulant microparticles by platelets and vascular cells and the increase in the global thrombin generation due to an acquired activated protein C resistance result in a highly prothrombotic scenario in patients with polycythemia vera and essential thrombocythemia. The acquired point mutation in the pseudokinase domain of JAK2 (JAK2V617F) in these disorders is variably associated with thrombosis and, more consistently, with elevations in WBC counts and alterations in biomarkers of blood-clotting abnormalities. The predictive value of these biomarkers for thrombosis remains to be established to identify subsets of patients at elevated risk who may benefit from prophylaxis with antithrombotic drugs.